About the cover: Cover is based on images of lungs from K-ras^LA1 mice exposed for four weeks to an aerosol containing a lentivirus construct encoding carboxyl-terminal modulator protein (CTMP). The top row contains images of lungs from 9-week-old mice, the images on the bottom are lungs from 13-week-old mice. The images in the left column are from control mice, the images in the middle column are from the vector controls, and the images in the right column are from mice that were administered lentivirus-CTMP. The arrows and circles indicate the location of adenocarcinoma. For more information, see article by Hwang and colleagues, beginning on page 1131.